The slaughter of four 70-year-old eels has "sickened and stunned" staff at Christchurch's Willowbank Wildlife Reserve.
Willowbank centre manager Dale Hedgcock said staff had noticed their popular eel display had been diminishing to the point where they could no longer let the public feed the creatures because there were none left to feed.
"There was an unproven suspicion that someone may be was taking them, but it couldn't be substantiated and there was always the thought in the background that perhaps these incredible beasts had finally decided to take the long journey to Tonga to breed," he said.
His worst fears were confirmed last week when he found two eels "stabbed to death" in the river.
Hedgcock was later alerted to a picture of two youths on Facebook of themselves on the reserve grounds with two dead eels in hand.
Staff were devastated to see their beloved eels "hanging dead on the end of spears held by gloating goons", he said.
Under the photo, the men had said they did not kill the eels to eat them but because they were "bored and looking for something to do".
"They made themselves out to be hunters of the highest order, catching eels that most could only dream of, rather than telling the cowardly truth that they stood over tame hand-fed creatures in a sanctuary and mindlessly slaughtered them," Hedgcock said.
The staff had worked for over 10 years developing the Styx River eel display, feeding up to 80 wild eels three times a day.
"They're not in a cage, they're just part of the river. They're free to come and go as they choose and we've worked hard to make it a safe place for them. Now that sanctuary has turned into a bloodbath," Hedgcock said.
"It's disgusting. There are four that we know about for sure, but there may be more."
Hedgcock said they had reported the crime to the police, who were treating it as a burglary.
"They had to break in. We are not sure exactly how they got in but we are taking this very seriously," he said.
"We have their names from Facebook so it was not the most clever move. The police said the evidence is pretty obvious. They are on our grounds."
The eels were estimated to be between 60-70 years old and weighed over 13 kilograms.
Long-finned eels are considered threatened and eel numbers throughout the country are on the decline.
Hedgcock said the reserve had released the information in the hopes that it would discourage others from "taking similar action".
He also hoped it would raise awareness about the endangered status of eels and stop others eeling in the Styx River.
- The Press